So, Damon is teasing a "spectacular kiss" in the season finale. I'm thinking it kind of has to be between one of the two "couples" being split up, either Sawyer and Kate or Jack and Juliet. (He did say it will be a boy/girl kiss. Hee, he knows us too well!) I'm kind of leaning towards Jack and Juliet, as they've only just started their romance and Sawyer and Kate aren't exactly "on" right now. They may not even get a goodbye scene, who knows?
And Jack/Kate wouldn't make much sense as a) she's just not that into him and b) they're leaving together! It doesn't seem to me that sharing a helicopter ride back to the mainland is the start of anything romantic between them. It's seemed pretty one-sided, for the most part.
Anyway, that's my spec on the subject.